1. Technical Field
This present application relates to a vacuum drum for use on labeling machines and on labeling machines for a wraparound labeling process, and to a labeling machine with such a vacuum drum.
2. Background Information
Background information is for informational purposes only and does not necessarily admit that subsequently mentioned information and publications are prior art.
Vacuum drums for use on labeling machines, for example on labeling machines that are realized to perform wraparound labeling, are described in the prior art. Basically, such vacuum drums are used for, among other things, applying the labels with a forward or leading end of the label (edge or side of the label) in the direction of rotation or revolution of the vacuum drum to the respective container as the container is moved past the labeling unit, whereby the label is then completely applied to the container, e.g. by rotating the container around its vertical container axis as the label is removed from the vacuum drum. The labels are each held on the vacuum drum by their leading label end or by a rear or trailing label end on a vacuum holder or vacuum pad. The distance between the corresponding vacuum holders for the leading label end and the rear or trailing label end on the peripheral surface of the vacuum drum, which is generally in the form of a circular cylinder, is thus essentially equal to the length of the labels to be processed. On the periphery of some vacuum drums, there is a plurality of vacuum holders for the forward end of the label, each with a corresponding vacuum holder for the trailing end of the label, so that a plurality of individual labels can be transferred to a plurality of respective containers during one full revolution of the vacuum drum.
For wraparound labeling, in which the labels completely surround the container in the area to be labeled and for this purpose are applied with the two ends of the label overlapping, one problem is that containers with different diameters in the area to be labeled or with different formats may use labels of different lengths. Consequently, the vacuum holders corresponding to each other for the leading end of the label and the trailing end of the label should be at a correspondingly different distance from each other on the periphery of the vacuum drum for the labeling of containers that have a different diameter.
For the conversion of labeling machines from labels of one length to labels of another length, e.g. when there is a change of format, it has therefore been desired up to now to replace the vacuum drum that was in use prior to a format change with a vacuum drum that is appropriate for the new label format. Simply on account of the significant weight of such vacuum drums, this process may require complicated handling and the expenditure of significant force. A suitable vacuum drum may also be available for each format, which also involves a significant amount of technical and mechanical complexity.